1. Field of Technology
Embodiments disclosed herein relate to audio systems, and more specifically to an audio system for reducing audio distortion of a loudspeaker.
2. Description of the Related Arts
A loudspeaker is a device that receives an electrical signal and converts the electrical signal to audible sound. Loudspeakers can include a voice coil that is inside of a magnet and is also attached to a diaphragm (e.g., a cone). When an electrical signal is applied to the voice coil, the coil generates a magnetic field that causes the voice coil and its attached diaphragm to move. The movement of the diaphragm pushes the surrounding air and generates sound waves.
For better sound fidelity, the sound waves produced by a loudspeaker should be proportional to the electrical signal applied to the loudspeaker. However, in a real loudspeaker, the movement of the diaphragm is not exactly proportional to the applied electrical signal, and this deviation leads to loss of acoustical fidelity. The loss of acoustical fidelity is especially pronounced with small loudspeakers, such as those found in mobile phones, tablet computers, laptops, and other portable devices.
There are several causes of the deviation between the electrical signal and the movement of the diaphragm. First, the coil and its associated parasitics are reactive and the magnetic field created by the coil varies depending on the frequency of the applied electrical signal. This results in a non-flat frequency response of the coil. Second, the effect of the magnetic field of the magnet on the coil is not constant as the position of the coil changes inside the magnet. As the coil moves backward and forward in response to the applied electrical signal, its position relative to the magnet changes. This changes the amount by which the magnetic field of the coil and the magnetic field of the magnet interact, resulting in movement of the diaphragm the extent of which is dependent upon the current position of the coil. Third, the springiness of the suspension supporting the diaphragm is not constant, and varies depending on how far it the diaphragm is displaced from its nominal position. All of these factors lead to increased distortion in the sound produced by a loudspeaker.